Liquid resistance, especially for electrical circuit breakers



July 5, 1966 A. LATOUR LIQUID RESISTANCE, ESPECIALLY FOR ELECTRICAL CIRCUIT BREAKERS 2 Sheets-Sheet 1 Filed Dec. 9, 1963 Fig 3 y 5, 1966 A. LATOUR LIQUID RESISTANCE, ESPECIALLY FOR ELECTRICAL CIRCUIT BREAKERS 2 Sheets-Sheet 2 Filed Dec. 9 1963 United States Patent 13 Claims. (cl. ass-222 .This invention relates to liquid resistances and concerns more particularly the variable resistances intended for .connection in parallel to the interrupting gap of electric circuit breakers.

It is already known to increase the interrupting power of a circuit breaker by mounting a resistance in parallel with the interrupting gap. In this case it is advantageous to employ a resistance which is capable of limiting very quickly, or even interrupting at the end of a very short time, the current which traverses it. For this purpose it has already been proposed to employ an absorbing resistance for electrical interrupters comprising at least one group of two electrodes connected by a liquid conductor of small depth, the contact surface with the liquid'of the one or more electrodes of at least one of the two poles of the resistance being small relative to the average section traversed by the current in the liquid conductor, so that the ohmic value of the resistance increases strongly when the density of the current at this surface exceeds a predetermined value, causing the formation of a gaseous sheath between these electrodes and the liquid.

It is an object of the invention to improve this known device which has not provided the expected advantages.

According to the invention the liquid conductor of a group of conductors is disposed between two receptacles of insulating material in the form of a plate or dish, nested one into the other in such a manner as to leave between them only a thin layer of liquid.

In some cases, particularly in order to allow the insulating breaker time to operate, it may be useful to retard the disappearance of the gaseous bubble and/or to increase its volume.

According to another feature of the invention this may be obtained by adding to the conducting liquid bodies which, under the influence of the heat discharge by the current in the vicinity of the electrode, are decomposed into inert gases and which recombine with difficulty. In the same spirit one may also dispose, according to another feature of the invention, in the vicinity of the electrode solid bodies whose gaseous decomposition pro ducts provide the same effect under the action of heat.

In order to avoid having an are created between adjacent electrodes of opposed polarity, one may interpose, according to another feature of the invention, between these electrodes, suitable partitions, for example baffles which avoid the direct contact of the gaseous bubbles which surround the electrodes.

Other arrangements pertaining to the invention and concerning in particular the form and the arrangement of the electrodes of the receptacles containing the conducting liquid, seals intended to retain the liquid and to evacuate the gas, and the like, will appear more clearly during the following description of several embodiments of the inventive concept without thereby limiting the generic scope of the invention to the specific details or elements of the embodiments selected for the purpose of illustration.

In the attached drawing:

FIG. 1 illustrates diagrammatically the application of the resistance according to the invention to a circuit breaker;

3,259,867 Patented July 5, 1966 FIG. 2 shows an axial section through a resistance according to FIG. 1;

FIG. 3 shows a plan view of a sub-assembly according to an embodiment of the invention;

FIG. 4 shows a section of a sub-assembly according to another embodiment of the invention; and

FIG. 5 shows a section of a sub-assembly according to another embodiment of the invention.

FIGURE 1 illustrates diagrammatically a circuit breaker according to the invention, the main interrupter being illustrated at 11. This interrupter is shunted by the liquid resistance 12 comprising two electrodes immersed in a conducting liquid, the contact surface between these electrodes and the liquid being small relative to the average section traversed by the current in the liquid. The resistance 12 is connected in series with the insulating interrupter 13 which is in the closed position when the main interrupter is closed.

The operation is as follows:

When the main interrupter 11 opens and while an arc extends between the contacts, the voltage applied to the resistance 12 is too weak to cause the development of the gaseous sheath which insulates the electrodes. However, at about the moment of the extinction of the arc the voltage surges and causes an influx of current in the shunt circuit which causes an acceleration of the arc extinction and maintains the voltage at the terminals of interrupter 11 at a small value for a brief moment. This permits the de-ionization devices of interrupter 11 to build a di-electric barrier which is sufficient to prevent definitely any re-lighting of the arc. During this time the voltage continues its surge to the terminals of resistance 12 and creates a current which increases until the moment where the gaseous insulating sheath appears around the electrodes of resistance 12, which causes the limitation or extinction of the current. The insulating interrupter 13 opens thereafter and permits thus a return to the initial stage of resistance 12. All this takes place as if at the breaking moment the main interrupter 11 were shunted by a resistance of small ohmic value becoming infinite or at least very large before the opening of the insulating interrupter.

It is evident that this type of operation is considerably affected by the value of the current traversing the circuit. In particular when the main interrupter must break a weak current this does not allow the formation of the gaseous sheath in the resistance 12 and the interrupter 13 must eliminate definitely this weak current. It is also necessary to employ an insulating interrupter whose breaking power may be limited to currents whose value is insufficient to cause the appearance of an effective gaseous sheath on the electrodes of the resistance.

FIGURES 2 and 3 represent in section and in plan view an embodiment of a resistance according to the invention. The resistance consists of a stack of receptacles 14 of insulating material of conical form nested one into the other in the manner of a stack of plates and containing each a certain quantity of conducting liquid L. The base of each receptacle is traversed in a tight manner by an electrode 15 disposed preferably eccentrically and in such a manner that one of the extremities is immersed in the liquid of its own receptacle while the other extremity is immersed in the liquid of the following receptacle. The eccentric arrangement permits a placement of one electrode alternately to the right and to the left of the median plane of the figure of the drawing which permits a reasonable spacing of the electrodes with a minimum hindrance in height. In the case where the spacing of the electrodes will still be insufficient to avoid the formation of an arc jumping from one electrode to the other, it is advantageous to provide partition 16, 17 of insulating material disposed preferably as baffles, and having the effect of ex may thus serve the role of electrodes.

tending the lines of flow of the current in the body of the liquid on the one hand, and to avoid the direct contact of the gaseous bubbles surrounding the electrodes on the other hand. In order to avoid that such partitions cause an extension of the current lines which would lead to an undesirable increase of the resistance, it would be advantageous to produce them by interposing between the electrodes a porous wall, such as the partition depicted in FIG. 5, which is easily permeable to the liquid but which forms a screen for the gases.

For di-electric reasons it is advantageous to give to the extremities of the electrodes a convex form or a semispherical form which approaches very closely the natural form of a gaseous bubble.

It will be noted that the receptacles 14 are only partially filled with liquid. This permits the provision of an expansion chamber 18 which limits the excess pressures during the operation of the apparatus.

In order to avoid the loss of liquid by splashing or by inclination during transportation, a seal 19 is provided between adjacent receptacles. However, it is necessary to provide a gaseous exchange with the outside atmosphere. This effect is obtained by constituting the joint from a material which is impermeable to liquids, but which is permeable to gas, for example a mineral felt treated with silicon.

FIGURE 4 represents another embodiment according to which the insulating receptacles are replaced by metallic receptacles 20 which may serve themselves as electrodes. For this purpose the outer surfaces and the inner surfaces of each receptacle are protected by a coating, an envelope or a layer of insulating material 21, 22. Each envelope is provided with openings 23 and 24 disposed eccentrically in such a manner that an opening 23 of an outer envelope corresponds, in the same bath of conducting liquid but on the other side of the median plane of the figure, with an opening 24 in an inner envelope.

The portion of receptacles 2t) exposed by the openings However, if it is necessary to employ electrodes of a metal which is different from that of the receptacles, the electrodes may be placed on the metallic wall of the receptacles themselves and be in contact with the liquid through appropriate openings 23, 24. As it has been indicated above the use of porous partitions or diaphragms permits not only bringing the electrodes closer but also placing them one in front of the other, which is advantageous from the point of encumbrance and of the symmetry of the current lines for the purpose of obtaining, all things being equal, the minimum resistance. FIGURE 5 represents this type of arrangement. A porous partition is illustrated at 25, the brackets 26, 27 serving to fix the partition in position.

In FIGURES 2 through 5 the resistance is shown in the form of a stack of identical elements. The elements are combined and interconnected in any suitable manner. In particular the stack may be lodged on the inside of an insulating tube whose ends serve to support the two extremities of the stack. In this case it will be advantageous for the purpose of increasing the di-eleotric strength of the gaseous sheaths to fill the tube containing the stack with a compressed gas.

The conducting liquid will preferably be chosen among the electrolytes which are good conductors, for example a solution of sulphuric acid. In this case the gaseous sheath is formed primarily of oxygen and hydrogen which, after the disappearance of the current, recombine very rapidly and create a void and consequently an almost instantaneous return of the liquid around the electrode. This phenomenon may be troublesome because it corresponds to a premature and useless picking up of the current. In order to avoid this or at least in order to give the insulating interrupter time to react, it is preferable to introduce into the liquid, either in suspension or in solution, bodies which are susceptible of liberating under the action of heat gases which recombine either with difliculty or only slowly. For example, an addition of colloidal carbon will produce during operation carbon monoxide which, in the presence of hydrogen, leads to a re-,

combination which is slower and more incompletethan the oxygen. In a further example, an addition of ammonium sulphate will cause a release of nitrogen which will contribute efieotively to the maintaining of a gaseous cover on the surface of the electrode. 7

It is also possible to dispose in the vicinity of the electrode a solid body whose gaseous decomposition products create the same effect under the action of heat. FIG- URE 4- is a good example of this arrangement, the envelope 22 being made of a suitable gaseous material. In this case the edges of openings 23, 24 act under the etfect of heat as an annular source of gas tending to maintain the gaseous bubble interposed between the liquid and the electrode.

It is appropriate to point out that each receptacle may contain more than one pair of electrodes. In particular if one desires to reduce the internal resistance of the device, each pole of a cell may comprise two or more electrodes connected in parallel.

Finally, in order to improve the evacuation of the gases which are released, one may provide electrodes in the vicinity of the surface of the liquid, and in such a way that they are immersed only partially in the liquid, in which case it would be advantageous to give them an elongate form.

What is claimed is:

1. An electrical device comprising at least one group of two electrodes respectively provided on two adjacent dish shaped electrically insulated receptacles each of said receptacles having generally the same size and shape and having walls defining a closed bottom flaring to define an open top substantially larger than said closed bottom, said receptacles being disposed one above the other, a liquid conductor in the lower of said receptacles, and said receptacles being nested one within the other with their bottoms and their electrodes in spaced relationship, the bottom of the upper receptacle being immersed in said liquid conductor to provide between said receptacles only a shallow depth of said liquid conductor which is substantially less than the height of said walls, and said electrodes extending into said liquid conductor so as to provide an electric current path between said electrodes through said liquid conductor.

2. Device according to claim 1, wherein said receptacles define at least in part a closed chamber therebetween.

3. Device according to claim 2, wherein said closed chamber containing said liquid is only partially filled with said liquid conductor.

4. Device according to claim 3, wherein said closed chamber is sealed for maintaining it under pressure.

5. Device according to claim 1, wherein a material susceptible of emitting a gas under the action of heat is disposed in said chamber.

6. Device according to claim 1 wherein said liquid conductor contains products which release a gas which recombines with difiiculty under the action of heat.

7. Device according to claim 2 including seals disposed between parts of said nested receptacles located above said liquid conductor, said seals being impermeable to said liquid conductor but permeable to gas for allowing a gas exchange between said closed chambers andthe atmosphere.

8. Device according to claim 1 wherein the walls of at least one of said electrically insulated receptacles are formed of a conducting material covered with an insulating material and comprising uncoated parts constituting electrodes.

9. Device according to claim 1 including bafile means interposed between said electrodes.

10. A device according to claim 1 in which the electrode provided on the upper receptacle traverses the bottom thereof.

11. A device according to claim 1 in which the electrode provided on the lower receptacle traverses the bottom thereof.

12. An electric resistance comprising a plurality of groups as set forth in claim 1, said groups being disposed one above the other and nested one in the other in such a manner that the lower receptacle of one group and the upper receptacles of the adjacent group nested thereunder constitute a group as set forth in claim 1, each of said electrodes being exposed to the exterior and interior of the respective receptacle.

13. An electric resistance according to claim 12, in which the electrodes of two successive receptacles are oflset horizontally one relative to the other.

References Cited by the Examiner UNITED STATES PATENTS 1/ 1908 Thomas 200-146 3/1916- Jackson 317-64 10/ 1921 Creighton et a1 317--6 3 12/ 1928 Lemmon 200146 5/ 1946 Wittlinger.

9/ 1948 Wittlinger ZOO-113.2

FOREIGN PATENTS 4/1949 Great Britain.

RICHARD M. WOOD, Primary Examiner.

ANTHONY BARTIS, Examiner. 

1. AN ELECTRICAL DEVICE COMPRISING AT LEAST ONE GROUP OF TWO ELECTRODES RESPECTIVELY PROVIDED ON TWO ADJACENT DISH SHAPED ELECTRICALLY INSULATED RECEPTACLES EACH OF SAID RECEPTACLES HAVING GENERALLY THE SAME SIZE AND SHAPE AND HAVING WALLS DEFINING A CLOSED BOTTOM FLARING TO DEFINE AN OPEN TOP SUBSTANTIALLY LARGER THAN SAID CLOSED BOTTOM, SAID RECEPTACLES BEING DISPOSED ONE ABOVE THE OTHER, A LIQUID CONDUCTOR IN THE LOWER OF SAID RECEPTACLES, AND SAID RECEPTACLES BEING NESTED ONE WITHIN THE OTHER WITH THEIR BOTTOMS AND THEIR ELECTRODES IN SPACED RELATIONSHIP, THE BOTTOM OF THE UPPER RECEPTACLE BEING IMMERSED IN SAID LIQUID CONDUCTOR TO PROVIDE BETWEEN SAID RECEPTACLES ONLY A SHALLOW DEPTH OF SAID LIQUID CONDUCTOR WHICH IS SUBSTANTIALLY LESS THAN THE HEIGHT OF SAID WALLS, AND SAID ELECTRODES EXTENDING INTO SAID LIQUID CONDUCTOR SO AS TO PROVIDE AN ELECTRIC CURRENT PATH BETWEEN SAID ELECTRODES THROUGH SAID LIQUID CONDUCTOR. 